SONIX SN8P2501D - Page 67

SN8P2501D
8-Bit Micro-Controller
SONiX TECHNOLOGY CO., LTD Page 67 Version 1.5
Watchdog timer application note is as following.
 Before clearing watchdog timer, check I/O status and check RAM contents can improve system error.
 Don’t clear watchdog timer in interrupt vector and interrupt service routine. That can improve main routine fail.
 Clearing watchdog timer program is only at one part of the program. This way is the best structure to enhance the
watchdog timer function.
 Example: An operation of watchdog timer is as following. To clear the watchdog timer counter in the top
of the main routine of the program.
Main:
…
; Check I/O.
…
; Check RAM
Err:
JMP $
; I/O or RAM error. Program jump here and don’t
; clear watchdog. Wait watchdog timer overflow to reset IC.
Correct:
; I/O and RAM are correct. Clear watchdog timer and
; execute program.
MOV
A, #5AH
; Clear the watchdog timer.
B0MOV
WDTR, A
…
CALL
SUB1
CALL
SUB2
…
…
…
JMP
MAIN